| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for cleaning an exhaust gas which enhances a NOx-cleaning performance under a lean atmosphere in which an adequate NOx activity is not displayed as long as a conventional method for cleaning an exhaust gas is employed. SOLUTION: A nitrogen oxide in an exhaust gas which contains an unburnt component coexistent with the nitrogen oxide and changeable in the quantity of oxygen to a case where the unburnt component is equal to a theoretical reaction amount and to a case where the quantity of oxygen is more than that is cleaned using a catalyst for cleaning the exhaust gas. This catalyst is composed of a catalyst 1 containing a composite oxide which contains at least one selected from a group of platinum, palladium and rhodium, and at least one selected from a group of iron, cobalt, nickel and manganese, and barium and lanthanum, carried on a fire-resistant inorganic carrier, and a catalyst 2 containing indium and/or gallium and cobalt, carried on an alumina oxide carrier. In addition, the catalyst 1 is arranged downstream from the exhaust gas while the catalyst 2 is arranged upstream from the exhaust gas. Further, the catalyst 1 is arranged in the lower layer, while the catalyst 2 is arranged in the upper layer. |
